Constitution and stability of Siberian permafrost

Mikhail Permyakov1 Albert Duchkov2

Institute of Petroleum Geology and Geophysics Novosibirsk, Russia

1permyakovme@ipgg.nsc.ru

2duchkovad@ipgg.nsc.ru

– Institute of Petroleum and gas Geology and Geophysics (IPGG) (Novosibirsk)

– Institute of Geocryology (Yakutsk)

– Institute of the Earth’s cryosphere (Tyumen)

– Institute of the Earth’s crust (Irkutsk)

Permafrost structure

Kazanstevskoe(QIII1)

interglacial

Zyryanskoe (QIII2)glaciation

Karginskoe (QIII3)interglacial

Sartanian (QIII-IV)glaciation

Holocene (QIV)

>50 40 30 20 15 10 5 0 th.y-s.w

arm

ing

cold

Climate fluctuation in Pleistocene and Holocene(according to N.V. Kind)

Relict permafrost was formed due to of inclement conditions in Pleistocene. At these time the huge ground massifs had been frozen on the surfaceand under the sea shallow. Then, during the Holocene warming permafrost was thawing from the surface, but the deep permafrost layer persisted as relict.

0°C0°C

Heat flow map of Siberia (mW/m2)

Geological structure q,mW/m2

Mean temperature (С) at a depth of (km) 0,5 1 2 3 5

West-Siberia plateSiberian platformVerkhoyano-Kolymsk area

533961

1385

291527

603057

924781

14082

130

Southern limit of the extent of the cryolithozone during different periods of the Quarternary (Kondratieva et al., 1993). 1 - Early to middle Pleistocene, 2 - Late Pleistocene (Sartanian time), 3 - Early Holocene, 4 - Climatic optimum of the Holocene, 5 - Late Holocene, 6 - Contemporary times.

E.S. Melnikov, K.A. Kondratieva,

G.F. Gravis, L.N. Kritsuk, S.F. Khrutskyi

Khanty-Mansiysk Yakutsk

Thickness of the Siberian permafrost. 1 - isolines of the lower boundary depth (depth of 0C isotherm), meters; 2 - the same for upper boundary (only in West Siberia), 3 - south boundary of permafrost.

Contemporary average annual surface rock temperature in Western Siberia

Surface temperature

Permafrost boundary

Permafrost upper boundary in Western Siberia

Permafrost boundary

Permafrost upper boundary depth

Permafrost lower boundary in Western Siberia

Permafrost boundary

Permafrost lower boundary depth

Permafrost thickness

Permafrost boundary

Permafrost thickness

CO2 HSZ Thickness

Permafrost boundary

CO2 HSZ Thickness

CH4 HSZ Thickness

Permafrost boundary

CH4 HSZ thickness

Modern parameters of the West Siberia permafrost along the meridianal cross section. A - Plots of air (Ta) and rock temperature (Ts) at depth of 15-20 mB - Permafrost (P) upper and lower boundaries

Ta

Ts

Temperature field of permafrost

Siberia: Temperature of air in the North of Russia(Pavlov, Ananieva, 2004)

Examples of the temperature profiles from West Siberia: A – from northern regions (stable permafrost), B – from regions which have non-stable permafrost (constant temperature, geothermal gradient about 0)

West Siberia: A-C – temperature profiles from relict (land-buried) permafrost; D - curves illustrate disintegration of relict permafrost.

A B C D

Examples of the temperature profiles from Vilyui and Predverhoyan depressions: A and C – stable permafrost, B – non-stable permafrost

ATemperature

BTemperature

CTemperature

Stability of permafrost

Change of temperature in dry (A) and water-saturated (B) rocks with increase of Ts from -5ºC up to 0ºC for 20 thousand years.1 - in both cases initial distribution of temperature; (A) 2-5 – temperature profiles in 5, 10, 15 and 20 thousand years after the beginning of change Ts; (B) 2-6 - temperature profiles in 4, 8, 12, 16 and 20 thousand years after the beginning of change Ts.

B

Temperature profile

Temperature TemperatureA

Q – heat flow below the phase boundary; Qf – heat flow in frozen rocks; H - the ice melting heat; W – ice content; V – rate of frost penetration or thawing.

Near the phase boundary Qf/Q = 1 + HWV / Q = N

N is a criterion of permafrost temperature field stability.

I.While permafrost is stable: V = 0, Qf = Q and N = 1

II.Degradation of permafrost due to a climate warming: V<0, Qf<Q, Qf/Q = N<1

III.Accretion of permafrost due to a cold snap: V>0, Qf>Q, Qf/Q = N>1

Qf/Q can be used as a tool for studying the temperature field stability of the frozen rocks and a course of permafrost evolution.

This technique was applied to different permafrost areas showing that N<1, i.e. permafrost degrades everywhere

Map of modern trends of air temperature increase in the North of Russia, ºC/yrLong-term analysis of meteo data (Pavlov, Ananieva, 2004) suggests that warming takes place everywhere (which results in permafrost thawing with various rate)

Possible increase of surface temperature (С) in Siberia if the global climate warming will take place in 21 century (according to Manabe, Wetherald, 1975, 1987; Balobaev, 1994)

North. latitude

Years

2000 2020 2040 2060 2080 2100

50 0,3 0,7 1,3 1,8 2,4 3,1

55 0,4 0,8 1,4 2,2 2,8 3,5

60 0,4 1,0 1,7 2,5 3,4 4,4

65 0,5 1,3 2,0 3,0 4,2 5,4

70-75 0,6 1,6 2,5 3,8 5,2 7,0

Prognosis of the temperature changes in different blocks of Western Siberia permafrost during 21 century under influence of the climate warming. 1 – temperature profiles from cold permafrost (Arcticheskaya site, Yamal), 2 - temperature profiles from non-stable permafrost without geothermal gradient (Kostrovskaya site), 3 - temperature profiles from relict permafrost (Urengoi)

Expected evolution of permafrost in Russia at the moderate (1-2,5 °C growth in 50 years) scenarios of climate warming to 2020 and 2050 (Pavlov, Gravis, 2000).

Seasonally frozen ground

Permanently frozen ground that will thaw by 2025

by 2050

relatively stable

Region Gas content, billion of m3

(min/max estimation)

Timan-Pechora 300/1450

Western Siberia 2530/6000

Eastern Siberia 2625/7400

Far East 745/2300

Total amount: 7200/17150

Rough estimates of expected gas content within the Russian permafrost

(V. Yakushev, 2009)

Thank you